Monday, September 10, 2012

Leslie Swipes By Bermuda, Heads For Newfoundland

Leslie's slow march through the Western Atlantic has caused the storm, which was a minimal hurricane for a few days, to weaken a fair bit as it churned up the waters beneath and drew up cooler water below the surface. Additionally, dry air aloft helped chomp away at the core of the storm -- leaving a hollow, but large tropical system that's more subtropical in appearance than tropical. Leslie has 60 mph winds as of 5 AM this morning. Regardless, it impacted Bermuda between Saturday night and Sunday, bringing three inches of rain to Bermuda as it passed by. Leslie is being pulled north and northeast ahead of the cool front that blew through here on Saturday (you can see that thin line to its west marking the front). The result will be Leslie's acceleration and likely transition to a nontropical system when it hits Newfoundland tomorrow.

Farther east, Michael continues to spin around in the Atlantic but it will likely not last much longer. Northerly wind shear will increase thanks to Leslie's large circulation and the result will be a storm that shears about. Also, the storm is being tugged west into that outflow from Leslie thanks to a ridge of high pressure building into the storm's north, so it can't escape by staying east of Leslie. The result in the coming day will be a weakening trend that also includes a gradual transition to a nontropical system, if it can survive the increasing wind shear. Given Michael's smaller size, the storm may not handle the incoming hostile environment all that well.

Elsewhere in the tropics, to Michael's southeast on the edge of the map is a large area of thunderstorms with a tropical wave. It is trying to develop a low pressure center with it as it cruises along to the west-northwest. This system may develop into Nadine over the coming couple of days but it will not impact the US. Steering in the atmosphere suggests that this will be pulled north, likely between 50 and 60 degrees longitude, with computer modeling backing up that thinking as the GFS pulls the storm to the north in three days' time.